Prior to the development of the present invention, as is quite well recognized in the passenger transit type railway car automatic mechanical type coupling art, most railway type passenger transit cars have generally been equipped to enable an automatic mechanical uncoupling of any pair of connected mechanical type couplers which may be disposed intermediate any predetermined pair of passenger transit type railway cars located within a train consist to be accomplished.
The normal operation of such prior art automatic mechanical type coupling mechanisms, during an uncoupling sequence thereof, is usually accomplished by the initiation of an application of a predetermined torque either in a direct fashion or in an indirect fashion to the shaft member of such mechanical type coupling mechanism. In the past, such predetermined torque, which is being applied to such shaft member, will be a torque which is at least sufficient to accomplish the rotational displacement of such shaft member. At that point in time, i.e., when such rotational displacement of the shaft member has been completed it will cause the mechanical type coupling mechanism to become disengaged and thereby permit the adjacently disposed ends of the railway cars to separate.
In the presently available prior art type of electrically operated automatic mechanical type coupling mechanisms, which are known to applicants to be in use, there is an electric motor utilized to provide the requisite amount of power required to accomplish such rotational displacement of such shaft member. In this known mechanical type coupling mechanism, such electric motor, through the utilization of both a predetermined gear reduction and a transformation of the output shaft member in order to sustain a generally parallel orientation to such shaft member of such mechanical type coupling mechanism, causes a rotational movement of an uncoupling cam member which is attached to such output shaft member.
In turn, the above described operating sequence will result in a predetermined torque being applied to a lever mechanism, which is connected to the shaft member of such mechanical type coupling mechanism, and thereby achieving the requisite amount of rotational displacement of such shaft member and the mechanical uncoupling of the adjacently disposed ends of a pair of passenger transit type railway cars.
The required shut-off function for such electric motor is controlled in this prior art mechanical type coupling mechanism arrangement by the use of a limit switch. Such limit switch is positioned in relatively close proximity to the uncoupling cam member and will normally be activated upon the completion of a 360 degree rotation.
One of the most significant problems encountered by the prior art control circuit portions for such mechanical type coupling mechanisms is that such control circuit portions are, by necessity, positioned in a location with respect to such mechanical type coupling mechanism where they will be exposed to a number of undesirable and/or detrimental environmental conditions. The detrimental conditions encountered by such control circuit portions and which are clearly related to the environment will at least include, for example, water and ice. It is known by applicants, for example, that when these particular environmental conditions are present that these prior art control circuit portions have not always been reliable.
In addition, these prior art control circuit portions for a mechanical type coupling mechanism have, in general, been found to require a significant amount of maintenance be performed in order to properly maintain them in both an acceptable and safe operating condition. Obviously, this extraordinary maintenance requirement will add to the overall cost of operating the passenger transit system. Furthermore, at least a first portion of this relatively high maintenance cost is passed on to the passengers who make use of the transit system, while a second portion of such maintenance cost is usually passed on to taxpayers at the local, state and national levels.
It is clear from the above discussion of the known prior art mechanical type coupling mechanisms that a need exists for an improved timed thrust mechanism for use on passenger transit type vehicles which is more reliable regardless of the environment in which it must operate.